Longitudinal diode end-pumped solid-state lasers stand out in terms of their high efficiency and a good beam quality. The ability to store relatively large quantities of energy at the same time enables the generation of millijoule pulses, with pulse durations of a few nanoseconds, by means of a Q-switch internal to the resonator. This means that such lasers are favored for the processing of materials. In particular, for laser engraving an excellent laser beam quality is indispensable in order to obtain a precise machining result. The generation of a stigmatic laser beam from the solid-state laser requires a stigmatic pump beam. The latter is in many instances generated in a process in which the strongly astigmatic and asymmetric beam parameter product of a diode laser bar is rendered symmetrical by means of beam shaper optics and finally is coupled into a multimode fiber by means of a spherical focusing lens. This fiber coupling fundamentally enables the spatial separation between the actual solid-state laser beam source, i.e., the solid-state laser resonator, and the pump light source. In particular, this spatial separation of solid-state laser resonator and pump light source is essential in the implementation of air cooled laser systems, in order to build highly compact laser heads of low weight, in which the solid-state laser resonator is located. The pump light source generates such a high heat output that large volume cooling elements of high weight are used. The removal of the pumped light source together with the necessary cooling unit to a separate power supply unit of the solid-state laser therefore enables a small volume structure for the actual laser head.
The optical connection between the power supply unit and the laser head is formed by means of the previously mentioned multimode fiber (for example, a glass fiber). In most cases, the interface between the power supply unit and the laser head is not defined solely in terms of the optical pump light connection. In fact, electrical data conductors are also used for the control of actuators in the laser head or for the transfer of sensor data. If another element that has to be controlled (e.g., a scanner) is located on the laser head then further electrical conductors are required. In other words, the laser head is connected both optically and also electrically to the power supply unit.
Electro-optical hybrid connection assemblies are used in avionics, in the telecommunications field, by the military, and in space travel. In hybrid connection assemblies, the optical interface is between single mode fibers with relatively small optical powers of typically 1-2 W and small fiber core diameters of about 7 to 50 μm. The “butt coupling” technology used in these hybrid connection assemblies with bent, uncoated fiber end surfaces functions well in this low power range.
Optical connection assemblies for optical fibers or optical wave guides are known. A known optical connector is the so-called F-SMA connector (also known as the SMA connector), which has been internationally standardized. The F-SMA connector takes the form of a screw-in connector in which the fiber is guided in a relatively long metallic ferrule with a pin diameter of 3.175 mm, and which is ground flat on the contact surface. The insertion loss that is achieved with this connector depends on a large number of criteria. Thus, for example, the damping in the case of light guides with a larger core diameter is significantly less than that for fibers of smaller diameter.